1. Field of the Invention
The present invention relates to a rewritable optical disk recording apparatus and a method for recording data on a rewritable optical disk.
2. Description of the Related Art
A DVD-RAM (digital versatile disk random access memory) has sectors each composed of an ID section including four physical identifications (IDs) and a recording section which data is recorded on and/or reproduced from. FIG. 12 illustrates an exemplified format of such a DVD-RAM. In the recording section, tracks wobble in the radial direction forming sine shapes at a cycle of 186 channel clocks, so that this wobbling of tracks is observed in a push-pull tracking error signal as a wobble signal. Specifically, as shown in FIG. 2, a wobble signal is observed in the portion of a wide-band push-pull tracking error signal corresponding to the recording section.
The above wobble signal is allowed to pass through a narrow-band bandpass filter to digitize the wobble signal. The digitized signal and a signal obtained by dividing an oscillating frequency of a voltage controlled oscillator (VCO) by 186 are phase-compared. The resultant phase difference signal is allowed to pass through a low pass filter and then returned to an input of the VCO, so as to constitute a phase locked loop (PLL) (hereinafter, such a PLL is called a wobble PLL), thereby to achieve phase-synchronization. As a result, the oscillation clock from the VCO serves as a channel clock frequency of a physical disk. By using the oscillation clock from the VCO as a recording reference clock for recording and reproduction of data, data can be recorded on the disk substantially in synchronization with the sectors of the disk.
When data is recorded on or reproduced from a disk using a fixed clock from a crystal oscillator, a synthesizer, or the like as a reference clock, the data recording or reproduction is directly influenced by variation factors such as a shift of the fixed clock, a variation in the rotation of a spindle motor, and a variation in the linear velocity due to eccentricity of the disk. When recording of data is influenced by any of such factors, it may become impossible to correctly reproduce the data written on the disk. In some cases, when recording of data is influenced by any of such factors, data may be written on the physical IDs, failing to read information originally written on the physical IDs.
On the contrary, when the wobble PLL clock described above is used for data recording, since the wobble PLL clock follows a variation in the rotation of a spindle motor and a variation in the linear velocity due to eccentricity of a disk, data which has absorbed all of the variation factors can be recorded.
However, if such a wobble PLL clock fails to be synchronous with the wobbling on the disk, using the wobble PLL clock as a reference clock may cause a problem, data may fail to be reproduced, or may be written on physical IDs.
As another problem, when a disk is defective, has dust attached, or poorly reflects light, a tracking error signal is not generated. This means that the wobble PLL clock loses one object for comparison, and thus the reliability of the clock itself is lost.
The optical disk recording apparatus of this invention includes: a first detection section for detecting a ID address cycle based on a timing of detection of an ID section of an optical disk; a second detection section for detecting a wobble cycle based on a wobble clock; and a state determination section for determining a state of the wobble clock based on the ID address cycle and the wobble cycle.
In one embodiment of the invention, the optical disk recording apparatus further includes a use determination section for detecting whether or not the wobble clock is usable based on the state of the wobble clock.
In another embodiment of the invention, the state determination section generates a threshold window based on the ID address cycle and determines the state of the wobble clock depending on whether or not a signal indicating the wobble cycle exists within the threshold window, and the use determination section determines that the wobble clock is usable when the signal indicating the wobble cycle exists within the threshold window.
In still another embodiment of the invention, the optical disk recording apparatus further includes a recording section for recording data, and recording stop/suspension determination section for determining whether or not the recording should be stopped/suspended based on the state of the wobble clock.
In still another embodiment of the invention, the state determination section generates a threshold window based on the ID address cycle and determines the state of the wobble clock depending on whether or not a signal indicating the wobble cycle exists within the threshold window, and the stop/suspension determination section stops/suspends the recording when the signal indicating the wobble cycle exists outside the threshold window.
Alternatively, the optical disk recording apparatus of this invention is for recording data on an optical disk having a track wobbled in a radial direction at a predetermined cycle in synchronization with a wobble clock by phase-synchronizing the cycle of the wobbling and an N-divided wobble clock (wherein N is a rational number). The optical disk recording apparatus includes: a failure determination section for determining whether or not a wobble signal has failed.
In one embodiment of the invention, the optical disk recording apparatus further includes a use determination section for determining whether or not the wobble clock is usable when the failure determination section determines that the wobble signal has failed.
In another embodiment of the invention, the optical disk recording apparatus reproduces the wobble signal recorded on the optical disk, and generates a digitized signal obtained by digitizing the reproduced wobble signal when the reproduced wobble signal has an amplitude equal to or more than a predetermined value, and the failure determination section determines that the wobble signal has failed when the digitized signal is not output for a predetermined time period.
In still another embodiment of the invention, the optical disk recording apparatus further includes a recording section for recording data, and a recording stop/suspension determination section for determining whether or not the recording should be stopped/suspended depending on the failure of the wobble signal.
In still another embodiment of the invention, the optical disk recording apparatus reproduces the wobble signal recorded on the optical disk, and generates a digitized signal obtained by digitizing the reproduced wobble signal when the reproduced wobble signal has an amplitude equal to or more than a predetermined value, the failure determination section determines that the wobble signal has failed when the digitized signal is not output for a predetermined time period, and the recording stop/suspension determination section stops/suspends the recording when the failure determination section determines that the wobble signal has failed.
In still another embodiment of the invention, the optical disk recording apparatus hold the wobble clock when the failure determination section determines that the wobble signal has failed for a predetermined time t1, and the optical disk recording apparatus makes the wobble clock unusable when the failure determination section determines that the wobble signal has failed for a predetermined time t2.
Alternatively, the optical disk recording apparatus of this invention includes: a wobble reproduced signal processing section for reproducing a wobble signal to output a reproduced signal; a digitizing section which does not output a digitized signal obtained by digitizing the reproduced signal when the reproduced signal has an amplitude less than a predetermined value or outputs the digitized signal when the reproduced signal has an amplitude equal to or more than the predetermined value; a first failure determination section for outputting a first failure signal when the digitized signal is not output for a predetermined time period t1; a second failure determination section for outputting a second failure signal when the digitized signal is not output for a predetermined time period t2; a wobble phase difference detection section for outputting a phase difference signal between the digitized signal output from the digitizing section and an N-divided output clock output from a VCO; a wobble PLL section for passing the phase difference signal output from the wobble phase difference detection section to the VCO via a low-pass filter; a PLL blocking section for blocking the wobble PLL section from passing the phase difference signal to the VCO, depending on the first failure signal; and a wobble clock usable determination section for determining whether or not the wobble clock is usable depending on the second failure signal.
In one embodiment of the invention, the optical disk recording apparatus holds the wobble clock when the failure determination section determines that the wobble signal has failed for a predetermined time t1, and the optical disk recording apparatus stops/suspends recording of information when the failure determination section determines that the wobble signal has failed for a predetermined time t2.
In another embodiment of the invention, the predetermined time t2 is longer than the predetermined time t1.
In still another embodiment of the invention, the predetermined time t2 is equal to or longer than the predetermined time t1.
Alternatively, the optical disk recording apparatus of this invention includes: a wobble reproduced signal processing section for reproducing a wobble signal to output a reproduced signal; a digitizing section which does not output a digitized signal obtained by digitizing the reproduced signal when the reproduced signal has an amplitude less than a predetermined value or outputs the digitized signal when the reproduced signal has an amplitude equal to or more than the predetermined value; a first failure determination section for outputting a first failure signal when the digitized signal is not output for a predetermined time period t1; a second failure determination section for outputting a second failure signal when the digitized signal is not output for a predetermined time period t2; a wobble phase difference detection section for outputting a phase difference signal between the digitized signal output from the digitizing section and an N-divided output clock output from a VCO; a wobble PLL section for passing the phase difference signal output from the wobble phase difference detection section to the VCO via a low-pass filter; a PLL blocking section for blocking the wobble PLL section from passing the phase difference signal to the VCO, depending on the first failure signal; and a stop/suspension section for stopping/suspending recording of information on the optical disk during the recording depending on the second failure signal.
According to another aspect of the invention, a method for recording data on an optical disk is provided. The method includes the steps of: detecting a ID address cycle based on a timing of detection of an ID section of the optical disk; detecting a wobble cycle based on a wobble clock; and determining a state of the wobble clock based on the ID address cycle and the wobble cycle.
In one embodiment of the invention, the method for recording data on an optical disk further includes the step of determining whether or not the wobble clock is usable based on the state of the wobble clock.
In another embodiment of the invention, the step of determining a state of the wobble clock generates a threshold window based on the ID address cycle and determines the state of the wobble clock depending on whether or not a signal indicating the wobble cycle is within the threshold window, and the step of determining whether or not the wobble clock is usable determines that the wobble clock is usable when the signal indicating the wobble cycle is within the threshold window.
In still another embodiment of the invention, the method for recording data on an optical disk further includes the steps of: recording data; and stopping/suspending the recording based on the state of the wobble clock.
In still another embodiment of the invention, the step of determining a state of the wobble clock generates a threshold window based on the ID address cycle and determines the state of the wobble clock depending on whether or not a signal indicating the wobble cycle is within the threshold window, and the step of stopping/suspending the recording stops/suspends the recording when the signal indicating the wobble cycle is outside the threshold window.
Alternatively, the method for recording data on an optical disk of this invention includes recording data on the optical disk having a track wobbled in a radial direction at a predetermined period in synchronization with a wobble clock by phase-synchronizing the cycle of the wobbling and an N-divided wobble clock (wherein N is a rational number). The method further includes the step of: determining whether or not a wobble signal has failed.
In one embodiment of the invention, the method for recording data on an optical disk further includes the step of: determining whether or not the wobble clock is usable when the step of determining whether or not a wobble signal has failed determines that the wobble signal has failed.
In another embodiment of the invention, the method for recording data on an optical disk further includes the steps of: recording data; and stopping/suspending the recording when the wobble signal has failed.
The xe2x80x9cstopping/suspendingxe2x80x9d as used herein indicates that either one of stopping and suspending is performed.
Thus, the optical disk recording/reproduction apparatus according to the present invention records data on an optical disk having a plurality of sectors each composed of an ID section formed of prepits and a data section for data recording/reproduction having tracks wobbled in the radial direction at a predetermined cycle, in synchronization with a reference clock obtained by phase-synchronizing the cycle of the wobbling and an N-divided clock (wherein N is a natural number) (hereinafter, such a reference clock is called a wobble clock). The wobble clock is made usable if the difference between the sector cycle determined by reproduction of the physical ID and the sector cycle determined by counting the wobble clock is within a predetermined range, or made unusable if it is not within the predetermined range.
Alternatively, in the optical disk recording/reproduction apparatus according to the present invention which records and/or reproduces data on and/or from an optical disk having tracks wobbled in the radial direction at a predetermined cycle in synchronization with the wobble clock, the wobble clock is made unusable if the wobble signal fails for a predetermined time period.
Alternatively, in the optical disk recording/reproduction apparatus according to the present invention which records and/or reproduces data on and/or from an optical disk having tracks wobbled in the radial direction at a predetermined cycle in synchronization with the wobble clock, recording is stopped or suspended if the wobble signal has failed for a predetermined time period during the recording.
Alternatively, in the optical disk recording/reproduction apparatus according to the present invention which records and/or reproduces data on and/or from an optical disk having tracks wobbled in the radial direction at a predetermined cycle in synchronization with the wobble clock, the wobble clock is held if the wobble signal has failed for a predetermined time period t1, or the wobble clock is made unusable if it has failed for a predetermined time period t2 wherein t2 greater than t1.
Alternatively, in the optical disk recording/reproduction apparatus according to the present invention which records and/or reproduces data on and/or from an optical disk having tracks wobbled in the radial direction at a predetermined cycle in synchronization with the wobble clock, the wobble clock is held if a portion of the wobble signal has failed for a predetermined time period t1, or recording is stopped or suspended if the wobble signal has failed for a predetermined t2 wherein t2 greater than t1 during the recording.
Thus, the invention described herein makes possible the advantages of providing (1) an optical disk recording apparatus and (2) recording data on an optical disk, in which the state of a wobble signal is determined and recording of data on an optical disk is suspended or stopped if the state of the wobble signal does not satisfy predetermined conditions, so as to realize stable recording of data on the optical disk.